I've read that it's efficacy diminishes over time. However, since I am frugal (some would use another word), I have been using the same bottle of rooting gel for years and years. I might have to break down next year and buy another.

I started 24 roses from cuttings outside this summer. I lost one for no apparent reason and another to squirrels. As to whether the rooting hormone was still doing its work, I have no idea, but my success rate was 96% (92% if I deduct the one the squirrel dug up). That's not too bad.

I hope someone answers your question with a little more science, and at least, referring to powder and not gel.

Thanks for the inadvertent joke, gilli. No, it happens to reside in the drawer of an old metal cabinet outside on the north side of the house alongside the rest of my cuttings paraphrernalia, out of view of most of the world. Temperatures there drop to minus 27 degrees celcius mid-winter (minus 16 Fahrenheit or so).
S.

The rooting powder is in most cases talkum with a growth hormone like Indol acetic acid or Indole butyric acid in the ppm range. The best way to keep it working is to store it under dry contidition free from microorganism. For longer periods of not using it - store it in a freezer.

Hi!
This may be too late to post, but just in case you're still curious...
I had the same question and learned the answer from a reliable soure (University of Washington). They claim that the talc version of the r/h has an 8 month shelf life, even if refrigerated (which I'm assuming extends it to the max). See link below if you want to read it (PDF) It's on page 5:

Beware! It's a PDF file so if you have acrobat reader it may load deadly slow...try getting the firefox free software 'foxit' to open PDF. It's free and about 200 times faster. You can find it on the Mozilla home page.
Cheers! Gonzo

Well, I think I'll try an experiment. I still have my powder from last year which has been in the shed with my other garden bits and pieces. I've just bought some more. I will try cuttings from the same plant with both and see if there is any difference.

If the rooting hormone powder is too old it will be ineffective in encouraging root development. The U.S. Forest Service says rooting hormone powder will keep for 18 to 24 months if stored in an airtight container in a dark, cool place such as the refrigerator.

The Forest Service advises gardeners to record the purchase date on the product container and to discard rooting hormones more than two years old.

To maximize effective life of the product, the Forest Service advises users to pour out a small quantity of the rooting powder in a separate container for dipping cuttings and not to return any leftovers to the main container.

My question is not regarding shelflife of rooting hormone but the astounding, sensational and even "disturbingly enviable" rate of success you have, Gilli in rooting.Could you care to let us know exactly what you do to bring about such success at propagation?I want to learn and copy it exactly,please.